For months, President Trump has claimed that U.S. Steel has announced plans to build more than six new plants. Throughout the midterm election, he repeatedly said that Democrats had signed onto an “open borders” bill. And he has long charged that millions of fraudulent votes were cast in the 2016 election.

Fewer than 3 in 10 Americans — including fewer than 4 in 10 Republicans — believe these or several other prominent claims by the president, according to the poll.

Only among a pool of strong Trump approvers — about 1 in 6 adults in the survey — did majorities accept several, though not all, of his falsehoods as true.

Among adults who say Fox News is one of their top two sources for political news, 33 percent believe in Trump’s false claims tested in the poll, on average, compared with 21 percent of those who say Fox is not a main news source.

Unlike many politicians who will abandon an untrue claim when fact-checked, Trump generally repeats his falsehoods. To capture this phenomenon, the Fact Checker this week introduced the Bottomless Pinocchio, a new category awarded to politicians who repeat a false claim so many times that they are, in effect, engaging in campaigns of disinformation. Fourteen of the president’s statements qualify for the list.

One of those — Trump’s assertion that he has started building his long-promised wall along the southern border, which he has said nearly 100 times — found little support in the poll.

The survey finds that 26 percent of Americans believe the statement, “Construction has begun on a wall along the U.S. border with Mexico.” About twice as many Americans, 51 percent, accurately selected the description that, “There is ongoing repair of fencing along the U.S. border with Mexico, but no wall is being built.” Roughly one-quarter said they were unsure.

Most of Trump’s base, however, believes that a wall is being built, with 56 percent of those who strongly approve of Trump’s job performance embracing that assertion.

Americans are most unsure about the false claim that U.S. Steel has announced plans to build more than six steel plants in the United States. Just 12 percent of adults say Trump’s claim is true, though fewer than one-quarter correctly identify the true statement that U.S. Steel has announced plans to restart two blast furnaces at one existing plant. Nearly two-thirds say they are unsure which claim is true.

President Trump is set to make a case to a national television audience Tuesday night for long-sought border wall funding; the impasse over the wall has led to a partial government shutdown. His remarks are scheduled for 9 p.m. Eastern and are expected to last about eight minutes and be carried live by all major television networks.